As shown in FIG. 1 a hitch pull type scraper 100 includes a pulling portion 101 such as a diesel engine powered cab or cabin. A scraper bowl 102 is coupled to the pulling portion (e.g., a cab or cabin) 101 by a hitch assembly 103. The hitch assembly 103 includes two H-links each having two journal bearings therein having a common shaft and another two journal bearings having another common shaft. The H-links moveably couple a linkage structure to a portion of the pulling portion 101. The hitch assembly 103 includes two vertical journal bearings disposed in a housing. Above one of the journal bearings is a thrust bearing. The two vertical journal bearings each employ a bronze sleeve disposed between a shaft and an interior surface defined by a bore in housing to facilitate rotational movement between the shaft and the housing. The thrust bearing employs a bronze bearing plate disposed therein to accommodate rotational movement of an upper thrust plate relative to a lower thrust plate.
A grease supply system (e.g., a configuration of tubes, valves and pressurizing devices) injects grease between the upper thrust plate and the lower thrust plate and the bronze bearing plate to maintain lubrication therebetween. The grease supply system also supplies grease to the sleeve in the journal bearings. The grease supply system can be damaged by projectiles such as rocks and stones that are propelled by the movement of the scraper 100. Use of a grease supply system leads to several undesired effects such as: 1) increased power requirements for the vehicle; 2) increased capital cost and maintenance related costs; and 3) environmental impact when old grease is purged from bearings, for example grease can seep out of the bearings during re-lubrication or due to leakage and can fall onto the ground. In addition, damage of the grease supply system can cause the flow of grease to the thrust bearing and journal bearings to cease and create undesirable grease discharge to the environment.
Thus, there is a need for an improved bearing system for the hitch assembly in a scraper vehicle.